1. Field of the Invention
This invention relates to protection of assets in protected areas from shock waves such as produced by explosive detonation.
2. Description of the Related Art
Explosive detonation may produce a shock wave that propagates outwardly from the point of detonation through a media such as air, liquid or a solid. The shock wave is a pressure wave that travels at supersonic speed in the media. The shock wave is characterized by an abrupt, nearly discontinuous change in the characteristics of the medium. Across the shock there is an extremely rapid rise in pressure, temperature and density of the flow. The shock wave carries a large amount of energy in a small volume that can be very destructive. However, the energy of the shock wave dissipates relatively quickly with distance. Furthermore, the accompanying expansion wave approaches and eventually merges with the shock wave, partially cancelling it out. In many explosives, the expansive wave expels metal fragments that provide additional destructive capability.
To protect assets such as buildings or large equipment from the shock waves and fragments resulting from nearby explosive detonations, mass may be placed around the protected area between the asset and an explosive detonation. The mass absorbs the energy in the shock wave through translation of the mass and/or internal friction due to deformation of the mass. Large amounts of mass are required to adequately protect the asset from potential threats. The “mass” may be earth/sand filled plywood walls, earth/sand filled tire walls or vertical reinforced concrete walls. Water filled bladders may be used to absorb the energy in the shock wave and convert it to a vertical spray of water. The mass also provides a barrier to the expelled fragments.